How to Recognize Carbide

Carbide is a compound that is formed from carbon and another metal, typically tungsten, although there are many types of carbides, all with slightly different properties. Carbide is noted for its strength and durability and is often used in parts for tools. Because it is designed for durability, carbide has some fairly unique characteristics and determining if an item is made from carbide is not very difficult. Learning to distinguish carbide from other materials can be a valuable skill, as recycling carbide is fairly profitable. 

Instructions

1.Hold a magnet to the item you are examining. If the magnet is attracted to it, the item is not carbide, it is iron or steel. However, sometimes carbide is used as a tip for an item, particularly saw blades, so this test is sometimes misleading.

2.Pick up the item and "heft" it. Carbide is very dense, and a carbide object will feel very heavy relative to its size. If you have a piece of steel that is a similar size to the object you are inspecting, the item will weigh about twice as much as the steel if it is carbide. This is the most conclusive test that does not risk damaging the item you are examining.

3.Scratch the item with a steel nail. The Mohs hardness scale is a method of measuring the hardness of different materials. Steel has a Mohs hardness that ranges between 5 and 8.5. Carbide will range between 8 and 9, depending upon the exact alloy that the carbide is made from. Typically, carbide will scratch steel and will not be scratched by steel. Carbide will scratch glass as well, as another way to test its hardness.

4.Examine the item. Carbide does not corrode under normal conditions and does not rust. Seeing either of these indicates that the item is made from some other metal.

5.Put the item to a grinder and watch the sparks. Sparks from carbide are short and dark red, and are very distinctive to carbide. This is a fairly definitive test, but is somewhat more dangerous than other methods of identification and can damage the item.

How Tungsten Carbide is Made

What Is Tungsten Carbide?
Tungsten is a heavy, gray metal with bluish overtones. When mixed with black carbon, tungsten carbide is created.
General Process
The compound is made by heating pulverized tungsten with black carbon, when hydrogen is present. Temperatures range from 2,550 to 2,900 degrees F or 1,400 to 1,600 degrees C. A common method for making the compound was developed in the 1920s in Germany and involves mixing powered tungsten carbide with cobalt. This mixture is then made into the required shape and heated to 2,550 to 2,900 degrees F or 1,400 to 1,600 degrees C. This heat melts the tungsten carbide partially, working as a cement. These tungsten carbide-cobalt creations are known by the names Carboloy and hardmetal.
Another Process
The tungsten and carbon is made into a powder using a pulverizer. The materials are then placed into a crucible and heated using an arc of electricity. The two materials then combine creating the tungsten carbide.
Uses of Tungsten Carbide
A gray, inorganic material, tungsten carbide functions as a hardener in armor-piercing projectiles, the sharp edges of drills and saws, and cast iron. Besides industrial uses, it is also used to create jewelry due to its hardness and deduced risk of allergic reactions among those with sensitive skin, among other desirable properties.

Hazards of Tungsten Carbide

The most frequently utilized hard metal in manufacturing today, tungsten carbide, is used to make a wide variety of products, including wedding rings, golf clubs and machinery. Tungsten carbide is favored by manufacturers because it is strong, durable and heat tolerant. It is made primarily of tungsten and cobalt and small amounts of other metals such as nickel. Workers exposed to airborne tungsten particles do not appear to have any adverse health effects, but exposure to airborne cobalt particles can have a serious impact on health.

The Difference in Tungsten Carbide and Cobalt Rings
1.Eye and Skin Irritation
When the eyes and skin are exposed to tungsten carbide, the result is irritation. In addition, repeated exposure can result in allergies to tungsten carbide, as well as to nickel and cobalt.
Respiratory Ailments
Inhalation of tungsten carbide dust can lead to nose, throat and lung irritation. Repeated exposure to tungsten carbide can lead to a range of serious respiratory ailments including asthma, pulmonary fibrosis and hard-metal lung disease.
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Organ Problems
When tungsten carbide is swallowed, it can lead to loss of appetite, nausea, vomiting and diarrhea. The China Tungsten Industry Association states that "reports outside the [tungsten carbide] industry suggest that ingestion of significant amounts of cobalt has the potential for causing blood, heart and other organ problems."
Reducing Exposure
When working with tungsten carbide, you can reduce your exposure by wearing clothing that covers your skin, including gloves and safety glasses; wearing a respirator or working in a well-ventilated area; cleaning work areas using a vacuum cleaner with a HEPA filter or other system that removes small particles from surfaces and the air; and always washing skin that has been exposed to tungsten carbide thoroughly.

The Difference in Tungsten Carbide and Cobalt Rings

Tungstencarbide has become one of the more popular nontraditional rings. Known for its strength and durability, the symbolism of tungsten carbide in wedding rings is undeniable. However, there are a number of rings on the market that are made using cobalt, rather than tungsten carbide, and that can create an entirely different sort of ring.
Tungsten Carbide

Tungsten carbide in its normal form is nothing more than a powder. Both tungsten powder and carbide powder have to be brought together and forged at very high temperatures to create the necessary bond that will result in a tungsten carbide ring. This process can be difficult and expensive, but it yields a high-quality product that will last for a long time.
Cobalt
Many rings that claim to be tungsten carbide are actually cobalt and carbide, or a mixture of tungsten, cobalt and carbide. Cobalt is much easier to form a bond with, and the forging can be done at a lower temperature for less cost.
Effects
There are a lot of downsides that come along with a tungsten carbide ring that has cobalt in it. For one thing, while you wear it, the cobalt in the ring will react with the natural oils produced by your skin. Cobalt rings will change your skin color, and over time they'll develop permanent oxidation spots that you'll never be able to scrub away. The rings might look nice at first, but within a week to a month depending on how much you wear it, the chemical reactions will occur and ruin its look.
Signs
There aren't many ways to tell just by looking at a ring whether or not it's pure tungsten carbide or a tungsten carbide and cobalt combination. The price is one of the most telling features, because rings made with cobalt are usually cheaper in price. The best way to make sure that you have a genuine tungsten carbide ring is to get a guarantee from the manufacturer, so that if your ring does have cobalt in it you can get a replacement at little or no charge.
Finish
Tungsten carbide rings are extremely strong and durable, and the same goes for their "permanent" finish. Pure tungsten carbide rings don't dent, scratch or lose their shine very easily. A tungsten carbide ring with cobalt in it will, however, so if you've bought a tungsten carbide ring that's lost its shine, even after a thorough cleaning, chances are there's cobalt in it.